Location of ground 119

[Gmule]

I am having an intermittent problem with the heater circuit for my O2 sensors. Sometimes I will have the DTC set for bank 1 and sometimes it will set for bank 2 I have checked the wiring diagram on all data but I can't seem to find ground 119 that all data says should be located on the RF front of engine. The only ground wire i have found on the front of the engine is at the thermostat housing. Is this ground 119?
any help with this would be appreciated.

 

[L31MaxExpress]

I am having an intermittent problem with the heater circuit for my O2 sensors. Sometimes I will have the DTC set for bank 1 and sometimes it will set for bank 2 I have checked the wiring diagram on all data but I can't seem to find ground 119 that all data says should be located on the RF front of engine. The only ground wire i have found on the front of the engine is at the thermostat housing. Is this ground 119?
any help with this would be appreciated.

I have had a couple of Vortec Tahoes and Suburbans with a large harness ground near the mechanical fuel pump boss way down low on the passenger side.

 

[Gmule]

Thank you I’ll give that spot a look

 

[L31MaxExpress]

Thank you I’ll give that spot a look

If you know your way around the older small block it is on one of the 2 passenger front engine mount bolts like a Tri-5 Chevy or medium duty truck used. I cannot remember if it was in the one that intersects the fuel pump pushrod or the other one. Either way they are like 2" apart and it should be easy to spot. Mine had a big metal L with about 10 ground wires and was the size of a battery cable where it entered the L.

 

[Scooterwrench]

If you know your way around the older small block it is on one of the 2 passenger front engine mount bolts like a Tri-5 Chevy or medium duty truck used. I cannot remember if it was in the one that intersects the fuel pump pushrod or the other one. Either way they are like 2" apart and it should be easy to spot. Mine had a big metal L with about 10 ground wires and was the size of a battery cable where it entered the L.

Geese. Gm should have used a ground bus like the hot bus on the firewall.

 

[east302]

This is on a 99 Tahoe?

The GM manual can be downloaded at this link (post #77):

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

According to that, 5.7L oxygen sensors ground at G105 which is down by the harmonic balancer and consistent with previous years. I didn’t see G119 mentioned in the manual, but maybe the link will help.

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[Gmule]

Thank you for that information
I had some time to dig into it and I found the open in the ground to the B2S1 circuit.
Looks like a rodent or a rub through
Now to get to that spot to fix it

 

[Gmule]

I hate rodents

 

[Road Trip]

Thank you for that information
I had some time to dig into it and I found the open in the ground to the B2S1 circuit.
Looks like a rodent or a rub through
Now to get to that spot to fix it

Good find, and thanks for sharing what you discovered!

Each failure that is troubleshot, fixed, & shared for everyone's edification is another
piece of the puzzle that, in total, gives us all a clearer picture of what it takes to keep
these GMT400s on the road literally decades after they were made.

****

Of course @east302 and @L31MaxExpress were on the money with both the schematics
& the physical location of the ground for the O2 sensors. Myself, coming up to speed on
the General's way of documenting the wiring harness was tough sledding at first. So many
grounds and Connectors seemingly scattered about willy-nilly, both physically & numerically?
There's gotta be some some sort of rhyme or reason?

But then I discovered the following big picture in the Wiring Diagrams section of the '99 C/K Service Manual:

Refer to Volume 4, Section 8, page 326:

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Voila! This really helps me while I'm trying to translate the abstract data from the wiring diagram to the physical layout
on the truck! Between this 'Truck Zoning' picture, the drawings of each ground & Connector location, and the
very clear pinouts...after wading around in it a bit I find the electrical wiring harness documentation to be better
than I hoped -- little to no guesswork involved. Simple is good, especially for an old dog like myself. :0)

Hope fellow up & coming sparky types find this helpful...

 

[Gmule]

As I learn the architecture of these vehicles I am really enjoying the simplicity of these systems.
Although I have been thoroughly spoiled by the technology that I use working on some ford vehicles.

Ford has a rendered wiring diagram based on DTC’s and only draws out those circuits and connectors related to that DTC. It is really nice at times to have the clutter removed from the diagram.